Last Night's Television - Why Did You Kill My Dad? BBC2; Five Days, BBC1

In the name of the father

Philip Hendy, a kindly, 75-year-old retired salesman, had just paid his newspaper bill and was about to set off for his allotment on a glorious Sunday morning in Bristol almost three years ago, when he was fatally stabbed in the back and neck by Stephen Newton, a mentally ill man with a string of convictions for assault and drug offences. It was a random, motiveless attack on a person Newton had never met, explored in detail that, as was more than hinted at by the title of the documentary and the name of the man who made it, was never likely to be objective.

But objectivity is an overrated virtue in documentarists. Moreover, Julian Hendy's troubling film, Why Did You Kill My Dad?, was not confined to his own family tragedy. Hendy talked to other people who had similarly lost loved ones to sudden and often horribly brutal acts of psychotic violence, and their stories tallied with his own. Presented as the villains of the piece, in every case, were the faceless bureaucrats administering the local mental health trust, who for a variety of reasons had apparently allowed a potential killer to stalk the streets. Not only that, but after the murders they had invariably kept a disrespectful distance, in some cases never making contact with the bereaved families.

I can see why Hendy so yearned to make this programme, and why he wanted to give these particular mental health trusts a kicking. The result was an exceptionally powerful hour of television, with about the right balance of analysis and emotion. Hendy was right to show us the home-video clips of his father playing with his grandchildren, and right, even, to let us accompany him to the police station where he collected his dad's personal effects, including a pair of blood-spattered spectacles. Whether that was a sequence of events set up purely for the camera doesn't really matter. Death, and particularly this kind of death, is an emotive business.

But then so, of course, is mental health. Several days before transmission an email dropped into my in-box, from the director of Time to Change, an organisation that campaigns against discrimination towards the mentally ill. It was what you might call a pre-emptive strike, acknowledging the importance of Hendy's documentary, but warning against the "damaging negative stereotype that automatically links severe mental illness with violence", a stereotype that "has prevented people from disclosing serious mental-health problems and getting the treatment they need". The implication was clear, that this documentary could lead to more rather than fewer random acts of psychotic violence. I can only imagine Julian Hendy's response to that particular charge.

Either way, it is a controversial and complicated issue, not especially illuminated by statistics. Hendy found that in Britain there are 50 cases a year of homicide in which the convicted killer had treatment for mental illness in the previous 12 months, but that doesn't allow for the many more cases where there was no treatment, or no conviction. I can quite see why Time to Change wants us to know that the overwhelming majority of mentally ill people are not violent, and the dangers arising from the assumption that they might be, but at the same time I went to bed last night haunted by the profound, ineradicable sadness in the eyes of Jim and Judy Cargill, a gentle couple from Buckinghamshire. Their son, Ben, was frenziedly stabbed to death on the eve of his 25th birthday six years ago, by a paranoid schizophrenic whose subsequent "indefinite detention" in a secure mental hospital lasted less than four years. That can't be right.

Mental health is one of the prongs in the many, many-pronged plot of Five Days, which began last night and unfolds every night this week in what is becoming a familiar scheduling strategy. For BBC1 and ITV1 in particular, it is a bold and potentially perilous ploy to "strip" a drama over five successive nights, and to sustain it, of course, the drama has to be an absolute belter. This new Five Days scores in that department, but not as heavily as ITV's latest effort, last year's brilliant Collision. With Collision, I believed in every plotline; here, I'm already struggling with one or two. For instance, would Danny (Matthew McNulty), a humble guard on a trans-Pennine commuter train, really be married to an Anglo-Pakistani girl as smart and exquisite as Nurat (Shivani Ghai)? Not in the world I come from.

But a few small gripes aside, including my perennial whinge about intrusive background music, Five Days is as classy a production as you would expect of anything featuring Suranne Jones, fast becoming one of our finest small-screen actresses, and supported here by heavyweights such as David Morrissey, Bernard Hill and Anne Reid. Gwyneth Hughes's story is notionally about a suicide and an abandoned baby, but there's race in there, and adoption, and Alzheimer's, and post-traumatic stress syndrome, and even train spotting. Which ought to be more than enough to keep us gripped until Friday.